1. Field of the Invention
The present invention relates to an ultraviolet light detection device for detecting ultraviolet light radiated to an occupant of a vehicle.
2. Description of Related Art
A large amount of ultraviolet light radiated from the sun may affect human health, so that it is recommended that human should not be exposed to too much ultraviolet light. However, when human is in a vehicle traveling outside, the human has to be exposed to ultraviolet light, because ultraviolet light is radiated inside of the vehicle through a window glass.
In order to reduce the radiation of ultraviolet light into the vehicle, a colored glass capable of blocking or absorbing sunlight is used as the window glass. However, a deep-colored glass hinders vision of a driver of the vehicle at night or under bad weather, so that the deep-colored glass may affect safety driving by the driver.
Here, JP-A-8-207569 discloses a sunlight-adjusting device for a vehicle. An occupant, e.g., driver, of the vehicle operates the device, if necessary, to adjust a light-transmitting rate of a window glass of the vehicle by changing an applied voltage. Thereby, ultraviolet light radiated to the occupant can be reduced, and vision of the driver can be secured.
However, because ultraviolet light is not visible light, the occupant cannot accurately determine the radiated ultraviolet light to be strong or weak. That is, the occupant sensuously estimates intensity of the radiated ultraviolet light based on brightness of outside. Therefore, the occupant may inappropriately operate the device, although strong ultraviolet light is radiated to the occupant.